Sheet lamination with transverse sheet bias to eliminate trailing edge coating debris

ABSTRACT

A method and apparatus for laminating media sheets to remove trailing edge coating debris as the carrier is removed from the laminated sheet involves imparting a transverse force to the laminated sheet to cause the sheet to abruptly straighten as the trailing edge of the sheet passes by a corner of a carrier separation bar at which the carrier is removed. The transverse force may be imparted by guides such as rollers defining a serpentine path through which the laminated sheet must travel.

CROSS REFERENCE TO RELATED APPLICATIONS

None.

BACKGROUND OF THE INVENTION

The present invention relates generally to the art of laminating sheetsof media such as copy paper with a protective glossy surface coat and,more particularly, to separating the carrier layer which transports alamination coat to the media sheet from a lamination stock roll.

Lamination stock comprises a flexible plastic carrier having laminationcoat material removably affixed to the carrier. The coating material isa micro thin plastic which includes an adhesive for retaining the coatmaterial on the media to be laminated. The micro thin coating materialfrequently does not cleanly separate form the trailing edge of alaminated media sheet. Undesirable coating material often extends andsubsequently break off in small pieces from the trailing edges oflaminated media sheets and the small pieces tend to statically adhere toequipment, clothing and sheets with which they come into contact. Thismaterial, known in the industry as TAG, is generally transparent and ofextremely light weight due to its thinness and thus tends to contaminatethe lamination area and result in imperfections in laminated sheets towhich the TAG has adhered. It has been noted that much of the TAG is inthe form of a thin tail or tail pieces which extend from the trailingedge of a sheet which has been laminated and from which the laminationcarrier has been removed.

It is accordingly an objective of the present invention to improve thelamination process by eliminating TAG particularly at the trailing edgeof laminated sheets.

SUMMARY OF THE INVENTION

The present invention therefore provides a method of laminating sheetsof media comprising the steps of:

a) feeding a carrier having a lamination coat removably adhered thereonto a bight between opposed lamination rollers;

b) moving a sheet of media to be laminated to said bight in surface tosurface contact with said lamination coat;

c) continuing to move said sheet and adhering said lamination coat tosaid sheet by application of pressure to said media and carrier by saidopposed rollers;

d) removing said carrier from a laminated sheet at a point downstream ofsaid rollers; and

The present invention further provides an apparatus for laminating asheet of media comprising:

a) a support for sheets of media to be laminated;

b) a pair of opposed lamination rollers and means for rotating saidlamination rollers to move a media sheet and a carrier having alamination coat thereon in surface to surface contact with said sheetthrough a bight between said rollers;

c) a carrier separator for guiding movement of said carrier duringremoval of said carrier from a laminated sheet, said separator having acorner for holding said carrier in engagement with a laminated sheet;

d) a puller for tensioning a carrier around said corner to remove acarrier from a laminated sheet; and

e) a sheet guide to cause a trailing edge of a laminated sheet toresiliently deflect and separate from removed carrier.

e) biasing said moving sheet transversely to a direction of sheetmovement to cause a trailing edge of said sheet to resilientlystraighten and move away from said carrier as a trailing edge of saidsheet passes said point.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross section view of a sheet laminationapparatus.

FIG. 2 is an enlarged view of a carrier and removable lamination coatadhered thereon to be applied to a media sheet.

FIG. 3 is a perspective view of a sheet biasing apparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In the following detailed description and in the several figures of thedrawing, like elements are identified with like reference numerals.

In the schematic representation of the sheet lamination apparatus seenin FIG. 1, the apparatus 10 includes a media feed tray or shelf 20 fromwhich individual media sheets are transported by suitable sheet movingapparatus (not shown) to be received in a nip or bight between opposedlamination rollers 50, 52. Those skilled in the art will understand thatopposed rollers may be replaced by equivalent means such as opposedbelts therefore, in this disclosure and the claims, the terms “roller”and “rollers” are intended to broadly encompass ordinary rollers, pluralcoaxial wheels, moveable belts which are trained around rollers andother mechanical equivalents which perform the same function.

A lamination stock supply reel 30 holds a wound web of layered materialcomprising a carrier 32 having a lamination coat 34 removably adhered tothe carrier layer and adhesive 36 for bonding the lamination material toindividual media sheets 38. Typically, the carrier 32 and laminationmaterial as well as adhesive 36 are a clear plastic sheet material whichadheres due to the adhesive to the laminated sheet from which thecarrier 32 is then removed and would onto a take-up reel 40 after themedia sheet 38 has been laminated. One or more guide rollers 42 serve toassist transport of the carrier 32 to the take-up reel 40. One or bothof the lamination rollers 50, 52 may be heated to a temperature notexceeding about 160° C. to simultaneously apply heat and pressure notexceeding about 4 lbs./sq. inch to the lamination web and media sheet 38to bond the lamination coat 34 to the sheet 38.

A carrier separator bar 80 is positioned downstream from the opposedlamination rollers 50, 52 and has a sharp edge or corner 54 around whichthe carrier 32 is bent during removal and transport of the carrier whichis pulled by powered rotation of the take-up reel 40.

As seen in FIG. 3, downstream of the lamentation rollers 50, 52 a sheetbiasing apparatus is provided which may be a roller frame 60 comprisedof spaced and pieces 62, 64 and transverse members 66, 68 affixed to theend pieces 62, 64. The frame supports the separator bar 80 and a feedlip or shelf 70 which, as shown, is part of transverse member 68, havingan upper surface 72 generally aligned in the direction of media travelwith the lowest corner of the separator bar 80 for receiving and guidingthe laminated sheet 38 to the separator bar 80.

In the presently preferred embodiment, downstream of the separator bar80 media guide rollers 90, 92 and a deflector bar 94 all supported onthe frame 60 together define a generally serpentine path through whichthe media must travel. The bend imparted to the media sheet transverselybiases the moving media sheet such that the trailing edge of the sheet,upon passing by the separator bar 80 is caused to move in a directiongenerally transversely (upwardly or downwardly as shown, for example) tothe path in which the media sheet passes the lower edge of the separatorbar 82 because the trailing edge of the media sheet 38 resilientlystraightens as it passes the separation corner on the separator bar 80at which the carrier 32 also abruptly changes direction during passageto the take-up reel 40.

In the embodiment seen in FIG. 1, the media sheet is bent in a directionto cause the trailing edge to deflect substantially upwardly parallel tothe removed carrier 32. It is of course possible to orient the guiderollers 90, 92 and deflection bar 94 to bend the sheet such that thetrailing edge resiliently straightens downwardly instead of upwardlyaway from the separation corner of the carrier bar 80 so that thetrailing edge of the sheet deflects downwardly away from the removedcarrier. In the embodiment shown, the transverse bias is applied to thesheet by use of rollers 90, 92 and the deflection bar 94 which may navea curved lower surface which provides a curved guide between the rollers90, 92. Means other than rollers and a deflection bar for biasing thesheet in a direction substantially transverse to its path of movementcan be envisioned. For example, transversely extending blocks having asquare or other angular configuration designed to urge the trailing edgeof the media sheet 38 in a direction to effectuate a clean separationfrom the carrier 32 without trailing edge TAG.

The deflection apparatus produces a transverse bend in the media sheet38 which causes the trailing edge of the sheet to abruptly snap or moveaway from the corner of the separator bar 80 at which the carrier 32 isremoved The inherent resilience of the laminated media sheet 38 causesan abrupt “snapping” action which substantially eliminates theobjectionable trailing edge debris known as TAG.

Persons skilled in the art will also appreciate that various additionalmodifications can be made in the preferred embodiment shown anddescribed above and that the scope of protection is limited only by thewording of the claims which follow.

What is claimed is:
 1. A method of laminating sheets of media comprising the steps of: a) feeding a carrier having a lamination coat removably adhered thereon to a bight between opposed lamination rollers; b) moving a sheet of media to be laminated to said bight in surface to surface contact with said lamination coat; c) continuing to move said sheet and adhering said lamination coat to said sheet by application of pressure to said media and carrier by said opposed rollers; d) removing said carrier from a laminated sheet at a point downstream of said rollers; and e) biasing said moving sheet to move a trailing edge of said sheet at said point transversely to a direction of sheet movement to cause said trailing edge of said sheet to resiliently straighten and move away from said carrier as said trailing edge of said sheet passes said point.
 2. The method of claim 1, wherein said media sheet is biased in a direction to cause said trailing edge to deflect toward said removed carrier.
 3. The method of claim 1, wherein said media sheet is biased in a direction to cause said trailing edge to deflect away from said removed carrier.
 4. The method of claim 1, comprising holding said carrier in contact with said sheet moving in a first direction and pulling said carrier away from said sheet in a second direction which intersects said first direction at an exterior angle not less than about 85°.
 5. The method of claim 4, comprising the step of using a rotating carrier take up toll to pull said carrier in said second direction.
 6. The method of claim 5, including applying lamination pressure to said carrier and said sheet at said bight not exceeding about 4 lbs./sq. inch.
 7. The method of claim 6, further comprising the step of heating at least one of said rollers to a temperature not exceeding about 160° C. during application of said pressure.
 8. Apparatus for laminating a sheet of media comprising: a) a support for sheets of media to be laminated; b) a pair of opposed lamination rollers and means for rotating said lamination rollers to move a media sheet and a carrier having a lamination coat thereon in surface to surface contact with said sheet through a bight between said rollers; c) a carrier separator for guiding movement of said carrier during removal of said carrier from a laminated sheet, said separator having a corner for holding said carrier in engagement with a laminated sheet; d) a puller for tensioning a carrier around said corner to remove a carrier from a laminated sheet; and e) a sheet guide to cause a trailing edge of a laminated sheet moving in a direction away from said carrier separator to resiliently deflect at said carrier separator away from said direction and separate from removed carrier.
 9. The apparatus of claim 8, wherein said sheet guide comprises spaced guides for bending a moving generally planar sheet transverse to the direction of movement of the sheet to urge a trailing edge of the sheet transversely of the plane of the sheet.
 10. The apparatus of claim 9, wherein said sheet guides include an angled surface positioned for engaging the leading edge of a sheet moving from said carrier separator.
 11. The apparatus of claim 10, wherein said angled surface is arcuate.
 12. The apparatus of claim 11, comprising a roller positioned transversely to the direction of movement of a sheet, said arcuate surface being on said roller.
 13. The apparatus of claim 12, wherein said guides further comprise a second roller and a curved guide between said rollers.
 14. The apparatus of claim 10, wherein said puller comprises a rotatable carrier take up roll.
 15. The apparatus of claim 14, wherein said separator comprises a bar extending parallel to said rollers, said corner having an interior angle at said corner of not more than about 95°.
 16. The apparatus of claim 15, wherein said separator bar has a corner radius not exceeding about 0.50 mm. 